Hull for boats



Feb. 20, 1968 P. MUSIC 3,369,512

HULL FOR BOATS Filed Oct. 18, 1965 5 Sheets-Sheet l FIG. la FIG. lb

PRIOR ART PRIOR ART HG. 2a FlG.2b

PRIOR ART PRIOR ART Feb. V20, 1968 P. MUSIC 3,369,512

HULL FOR BOAT 5 Filed Oct. 18, 1965 s sheets sheet 2 Feb. 20, 1968 P. MUSIC 3,369,512

HULL FOR BOATS Filed Oct. 18, 1965 5 Sheets-Sheet 3 OFFSET CHART HEIGHTS HALF-BREADTHS STATION KEEL CHINE#1 CHINE#2 SHEER CHINE#1 CHINE#2 SHEER 0 1 3/4" 6 3/4" 1'3 g" 1' 5 1' 2'1--" 1'5 5/8 1 11" 114" lg 1'6" 2'1 3/4" 1' l0" 2 3; lllon 2'25." 0;"

FIG. I2

Uie States Patent Ofiice 3,369,512 Patented Feb. 20, 1968 4 Claims. c1. 114-56) This invention relates to hulls for high speed wafer borne craft and to sail boats and in particular, to inboard and outboard speed-boats.

In the history of the development of power boats there has been a continuous compromise between the attainment of maximum speed for a given propeller horsepower and the improvement in cornering ability and the ability to take rough waters with the minimum of buffetmg.

An examination of conventional power boat hulls shows that the planing bottom is attractive from the point of view of reaching highest possible speeds with a given shaft horsepower, but at the same time, such planing hulls are very often unstable in cornering and in rough water. The reason for this is that regardless of the speed and attitude of a boat there is a certain required displacement of water in order to support the boat. This displacement may to a certain extent, be reduced by the elevation of the hull due to forward motion. When such a planing hull is cornering the planar surface of the hull is angled by inward heeling of the boat and the planar surface tends to want to climb up onto the surface of the water due to the radial velocity component of the boat with respect to the centre of the turning radius. As such, a hull climbs further onto the surface of the water, the effectiveness of the keelson, and indeed the wetted area of the underside of the boat becomes even less effective to prevent further side-slipping. Again, in order to provide the necessary displacement to support the front portion of the boat, the portion of the underside of the hull on the inside of the radius of turns has to provide all the required displacernent. The inside portion of the hull, therefore, tends to dig deeper into the water in order to provide this necessary displacement. Needless to say, a boat of such design will tend to alternately rise and fall about some nominal displacement and due to inertia of the hull such phenomena produces pitching of the boat in high-speed turns. The above mentioned phenomena appears to apply to both hard chined boats and conventional round bottomed boats.

Another aspect of bad cornering with conventional power boats lies in the shape of the bow. When a conventional hull heels inwardly during a turn the inner half of the boat, taken along the plane of symmetry, provides the sole means of supporting the hull during the turn. Thus, when a conventional hull is being turned, the curvature of the hull immediately below the bow sheer itself becomes equivalent to the upswing on the underside of the boat when the boat is non-heeled. This curvature under the bow sheer has generally an undesirable shape for providing a good compromise between displacement and planing effect, with the result that a boat subject to a fairly large amount of drag immediately the boat is placed in a heeled turn. This, of course, reduces the speed of the boat violently and the transom and engine tends to be lifted higher in the water due to the increased drag :at the front of the hull. The result of this is that the propeller tends to cavitate and the combination of the two phenomena tends to make turning very ineffective and very unstable. Since the above mentioned side-slip phenomena tends to cause the boat to ride up at the bow due to the radial components of the turn and, as just discussed, the drag of the bow on the inside half of the boat tends to increase with the result that, as stated above, the

transom tends to be lifted out of the water, the two phenomena interact causing a side-skipping of the stern during the turn.

The conventional power boat hulls suflfe-r to a greater or less extent in the manner of these falts.

In principle, the present invention contemplates providing a hull wherein the effectiveness of the upsweep of the hull immediately below the bow sheer remains substantially the same whether the boat is upright during a straight run or heeled over during a curve. Further, the present invention contemplates a hull which is substantially free from buifeting and side-skipping during cornering and which is provided with a plurality of hard chines having a novel disposition whereby side slip during cornering is considerably reduced and wherein the angle and depth, or draft, of the transom and engine is not violently changed during turning. Prototype boats built in accordance with the present invention have exhibited very considerable impr-ovements in general performance in comparison with conventional power boat bulls. The invention further provides a hull having improved mechanical rigidity, a more economical use of structural materials and a simplified building technique.

It is an object of one aspect of this invention to provide a hull, particularly for a power boat, which hull has improved genral performance and particularly improved performance during cornering.

In accordance with the foregoing aspect of the present invention, the invention consists of a hull having a lower water engaging surface terminated at one end by a bow and at the other end by a stern, a keelson, a sheer and a plurality of lower hard chines disposed substantially parallel to said keelson in plan view and each extending substantially from said stern to said bow-sheer.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings:

FIG. la is a front view of a conventional hard chined boat on even keel.

FIG. lb is the hard chined boat shown in FIG. la but heeled over in a turn.

k FIIG. 2a is a conventional soft chined boat on even FIG. 2b is the same hull as shown in FIG. 2a but with the boat heeled over in a turn.

FIG. 3a is a diagram showing the angles between side panels on a hard chined boat built in accordance with itihelpresent invention, the hull being shown on an even FIG. 3b shows the same hull configuration as shown in FIG. 3a, but with the boat heeled over in a cornering.

FIG. 4a shows a hull similar to that shown in FIGS. 3a and 3b but having additional inturned side panels adjacent the gunwales.

FIG. 4b shows the same hull configuration as shown in FIG. 4 but with the boat heeled over in a cornering.

FIG. 5 shows suitable rib members for use in the hull shown in FIGS. 4a and 4b.

FIG. 6 is a side elevation of a power boat built in accordance with the present invention.

FIG. 7 shows a plan view of the boat shown in FIG. 6.

FIG. 8 shows a rear view of the hull shown in FIGS. 6 and 7 but with the hull slightly heeled over.

FIGS. 9 to 12 are working layout drawings for the novel hull.

Referring now to FIG. la there is shown a conventional hard chined boat on even keel. The boat, generally indicated at 1 includes a stem 2, a keelson 3, side panels 4 and bottom panels 5 separated by the hard chine 6.

Referring now to FIG. 1b the same hull is shown heeled inwardly in a cornering. It will be seen that the keelson 3 is now clear of the water level, indicated at 10, and

that the hard chine .6 has assumed the role of the keelson 3. However, as the boat moves forward, the hard chine 6.

is no longer cutting the Water symmetrically as it does when the boat is moving. forward without heel. In conse quence of this, the hard chine 6 has an asymmetrical effect in the manner in which it cuts through the water. That is, the effective bottom of the boat now becomes equivalent to two surfaces represented by a bottom panel and side panel 4 which are not separated by a substantially vertical bow line equivalent to the stem 2, and such a vertical bow line could be indicated as by dotted lines 11. This asymmetrical approach of the water to the front of the boat as the latter moves forward gives rise to severe instability. Again, as discussed in the introduction, during a turn the boat will tend to side-slip in the direction of arrow 12 due to centrifugal force. As the boat side-slips in the direction of arrow 12, bottom panel 5 presents to the water a lateral planing surface indicated by dotted line 13. The boat tends to be lifted by this planing surface thereby increasing the heel of the boat. As the boat is subject to further heeling in consequence of this effect, the side panel 4, which is not a planing surface, presents an extra amount of drag on that part of the boat on the inside of the radius of curvature of the turn and this tends to bury the bow of the boat and-to raise the stern and engine higher in the water. For the various reasons discussed above, such conventional boats are very unstable in turning and lose considerable speed due to the utilization of the various members of the hull in a very inefficient manner.

Referring now to FIG. 2a there is shown the crosssectionof a conventional soft chined boat generally indicated at having a stem 21 and curved sides 22. When a hull of this type heels over in a cornering, as shown in FIG. 2b it will be seen that the wetted area of the hull as indicated at 22b, increases so that the half of the boat on the inside of the radius of curvature of the turn is subject to additional drag which drag tends to bury the bow of the boat in a manner as discussed in connection with the hard chine boat shown in FIGS. 1a and 1b. Again, the outward drift of the boat in the direction of arrow 25, due to the centrifugal effects tends to cause the angle of heel to increase by virtue of an apparent lateral planing surface as indicated by dotted line 23. In

some respects, such a hull shows a slight improvement.

over the hard chine boat as shown in FIGS. la and 1b in view of the fact that the wetted area is substantially symmetrical about dotted line 24. However, the centre of gravity of the boat is on the outside of this dotted line so that the boat will tend to roll each side of an average position during a turn.

Referring now to FIG. there is shown the novel configuration of a boat built in accordance with the present invention. Here a blow 30 is shown together with lower panels 31 and hard chines at 32. However, unlike the configuration shown in FIGS. la and 1b the chines do not sweep inwards towards the blow, but sweep forward and upwards to meet the bow sheer 33. Further, the chines 32 remain substantially parallel to the keelson identified at 34. It will be seen, in FIG. 3b, that when this hull is heeled over during a turn, not only is there a single flat planing surface, represented by panel 31, in contact with the water, but that the upper panel 35 on the inside of the curve is inclined away from the water are substantially the same angle as is the lower panel 31, on the outside of the curve. The disposition of the hard chines ensures that the lower panel 31 which becomes substantially parallel to the surface of the'water in the turn, slopes up at the front in a manner similar to the front of a water ski and the panel 31 behaves in substantially the same manner as the latter.

Referring again to FIG. 3a it will be seen that the angle between the two lower panels 31 is substantially the same as the angle between each of the lower panels 31 and its associated upper panels 35.

Referring again to FIGS. la and 1b, it was seen that when a conventional hard chine boat heels over in a turn a hard chine 6 tends to become the bow of the boat and the true bow is clear of the water.

In FIG. 3b it will be seen that the normal function of the how, so far as dividing the flow of water is concerned, is now shared between the bow 3G and the hard chine 32. However, while both of the bow 30 and the hard chine 32 are slightly inclined to the surface of the water, they actually rise above the surface so that their combined effect on the direction of flow of the water beneath the underside of the hull is substantially negligible. Any tendency to side-slip during cornering is consequently somewhat inhibited by the steeper angle that the outer lower panel 31 now makes with water, an angle indicated at B in FIG. 3b. A boat built in accordance with the configuration shown in FIGS. 3a and 3b is found to have excellent cornering ability, and substantially free from side-slip and buffeting.

Further advantage is experienced if splash rails are provided as shown at 32a. Such rails increase the lifting ability of the hard chines and also reduces the amount of water carried up onto the side panels 35 and spread thereupon by wind effects. Also such splash rails act as guards.

Referring now to FIG. 4 there is shown a further hull in accordance with the present invention which includes yet another hard chine 40 extending from the stern to the sheer and again disposed parallel to the keelson 34. Below the upper hard chine 40 is the previously mentioned side panel 35 and above the hard chine 40 is a further panel identified as a gunwale or upper panel 41 which makes an acute angle with panel 35. Panel 41 extends in wardly from the hard chine 40 towards the centre of the boat and performs a primary purpose to enable the boat to heel over further so that the side panel 35 becomes parallel to the surface of the water as shown in FIG. 4b without water entering the inside of the craft. This configuration also provides extreme rigidity in the structure of the boat, since it provides for a further longitudinal member spatially set inboard of the corresponding longitudinal members supporting the hard chine 40', the side panels 35 and gunwale panels 41. Such disposition of the longitudinal members increases the transverse moment of inertia of the hull.

Referring now to FIG. 4b, there is shown a hull in accordance with that shown in FIG. 4a wherein the hull is heeled over, in a cornering so that the side panel 35 is substantially parallelto the surface of the water 10. In a manner similar to that shown in connection with FIG. 3b the bottom panel 31 and the gunwale panel 41 each extend upwardly at similar angles to the surface of the water and both these angles are fairly large, one such angle being indicated in FIG. 4b at 5. Here again side panel 35 now acts in a manner very similar to water ski, since this panel curves upwardly to meet the bowv sheer. The boatwill be lifted by a planing action by that portion of the side panel 35 remaining in contact with the water. The hard chine 32, separating the lower side panel 31 and the gunwale panel 41, acts in a very stable manner and any tendency to side-slip during cornering .is sub stantially inhibited by the action of the hard chine 32 and the lateral planing angle. Again, it is envisaged that splash rails 32a and '43 may be included adjacent the hard chines.

Referring now to FIG. 5 there is shown constructional details at one station of a boat built in accordance with FIGS. 4a and 412. Such construction permits the use of a pair of lower rib members 51, intermediate rib members 52 and gunwale rib members 53. The angulation between rib members 52 and 53 provides considerable rigidity to the. hull wherein no adverse effects are felt during very fast cornering with the hull supported entirely by the upper side panel 35. A portion of coaming is shown at 54.

Referring now to FIG. 6, FIG. 7 and FIG. 8 there is shown general configuration of a power boat built in accordance with the present invention. As discussed in connection with the previous figures the boat includes a keelson 34, hard chines 32 and 40, a bow sheer 33 and coaming at 54. FIGS. 9, 10, 11 and 12 show typical proportions for a boat built in accordance with the present invention, wherein there is provided a power boat hull combining the best characteristics of both displacement and planing types of boats. The novel hull is provided with a deep V bottom of almost constant angularity from stem to transom and a bottom contour which gives a proportional reduction in draft as the forward speed increases and substantially eliminates pounding thereby. Further, the contour of the hull is such that it provides a minimum resistance to wind due to the presentation to the wind of a surface which is less flat than is the case with conventional hulls. Again, the novel hull reduces wave action While still providing greater stability and excellent planing characteristics. Further, the invention provides a boat having an almost constant amount of free board even when the boat is heeled over on one side and by aligning the hard chines substantially parallel to the keelson, construction is rendered more simple and economical of materials, at the same time, sheeting stresses are relieved due to the reduction of compound curves.

It has been shown that the invention provides a hull wherein the curvature of bottom of the hull, at the bow, sweeps from the stem to the chine and again from the chine to the sheer. This feature means that there is less drag resistance at the bow end, which in turn means that the boat thereby achieves greater lifting and easier maneuverability in turns especially in rough water compared with a conventional design of a boat wherein the bow presents a blunt side which is required to push the water both in the direction of the turn and also in the direction away from the turn.

Whilst the present invention has been described with reference to embodiments having one or two hard chines on each side of the hull, it will be obvious to those skilled in the art that one or more additional chines may be added providing always that the angle between the associated side panels, measured at each chine are substantially equal to one another and again substantially equally to the angle between the two lowest side panels adjacent the keelson. In will be further obvious that a boat built in accordance with the present invention may be formed by all conventional methods of boat building including steel, aluminum, wood, fibreglass or reinforced fibre-glass.

I claim:

1. A hull having a lower water engaging surface terminated at one end by a bow and at the other end by a stern, a keelson, a sheer, and plurality of lower chines disposed substantially parallel to said keelson in plan view and each extending substantially from said stern to said sheer, said chines dividing said hull into flat planing surfaces.

2. A hull as defined in claim 1 wherein either half of said hull each side of the plane of symmetry comprises at least two lower side panels, said two lower side panels having inboard surfaces disposed with a selected obtuse angle therebetween.

3. A hull having a lower water engaging surface terminated at one end by a bow and at the other end by a stern, a keelson, a sheer, a plurality of lower chines disposed substantially parallel to said keelson in plan view and each extending substantially from said stern to said sheer, and hull on each side of the plane of symmetry passing through the keelson comprises at least two lower side panels, said two lower side panels having inboard surfaces disposed with a selected obtuse angle therebetween, an upper chine and an upper side panel disposed above said upper chine, said upper side panel and the upper one of said lower side panels adjacent said upper chine having a selective acute angle therebetween.

4. A hull having a lower water engaging surface terminated at one end by a bow and at the other end by a stern, a keelson, a sheer, a plurality of lower chines disposed substantially parallel to said keelson in plan view and each extending substantially from said stern to said sheer, said hull on each side of the plane of symmetry passing through the keelson comprises at least two lower side panels, said two lower side panels having inboard surfaces disposed with a selected obtuse angle therebetween, the inboard surface of the lower one of said side panels on one side of the hull and the corresponding inboard surface of the lower one of said side panels on the other side of the hull are disposed at a selected angle, each of said lower one side panels being disposed adjacent the keelson, said selected angle between the lower one side panels at the keelson being substantially the same as said selected obtuse angle between the inboard surfaces of said two lower side panels wherein the inboard surfaces of adjacent lower side panels are disposed at substantially the same selected obtuse angle at the lower hard chines and the keelson.

References Cited UNITED STATES PATENTS D. 113,458 2/1939 Grant 96 X 2,379,883 7/ 1945 Clement 96 3,237,581 3/ 1966 Mosely l1456 FOREIGN PATENTS 1,057,486 5/ 1959 Germany.

ANDREW H. FARRELL, Primary Examiner. 

1. A HULL HAVING A LOWER WATER ENGAGING SURFACE TERMINATED AT ONE END BY A BOW AND AT THE OTHER END BY A STERN, A KEELSON, A SHEER, AND PLURALITY OF LOWER CHINES DISPOSED SUBSTANTIALLY PARALLEL TO SAID KEELSON IN PLAN VIEW AND EACH EXTENDING SUBSTANTIALLY FROM SAID STERN TO SAID SHEER, SAID CHINES DIVIDING SAID HULL INTO FLAT PLANING SURFACES. 